Definition of: river

(riv′ər) noun
1. A large, natural stream of water, usually fed by converging tributaries along its course and discharging into a larger body of water, as into the ocean, a lake, or another stream. ♦ Collateral adjective: fluvial.
2. A large stream of any kind; copious flow. See synonyms under STREAM.
—to sell down the river
1. Formerly, to sell (a Negro slave) into unsparing and rigorous servitude: from the severe conditions on the lower Mississippi cane and cotton plantations.
2. Hence, to betray the trust of; deceive.
—to send up the river To send to the penitentiary: from the fact that Sing Sing is up the Hudson from New York. [<OF rivière <LL riparia <L riparius. See RIPARIAN.]